Marin forecast: Wet, wild 'Pineapple Express' weekend

The first wave of a "Pineapple Express"-style subtropic storm system surged through Marin County Thursday morning, dumping more than an inch of rain. Forecasters say a lot more rain is on the way during the weekend.

"It won't be a drought buster, but it may put a dent in it," said National Weather Service forecaster Bob Benjamin. He said a "real soaker" moving in from the central Pacific could bring 3 to 4 inches of rain over the weekend.

No one was injured when several rocks toppled into cars on the Waldo Grade, where rockslides have been a continuing problem. Other incidents included minor flooding on San Clemente Drive in Corte Madera.

"There will definitely be some significant rainfall," Benjamin said of the next storm, with light showers beginning as early as Friday and continuing on and off through Sunday or Monday with "light, moderate and periods of heavy rain."

He expects "stream advisories" will be posted and some local flooding as drainage systems are tested by the first significant storm of the season, with breezy conditions along the coast but no heavy wind.

"There is a high likelihood of small stream flooding" this weekend, Benjamin said. "It's going to be fairly exceptional rain ... almost a Pineapple Express" that taps into subtropic moisture, he said. "It's going to be an atmospheric river."